The reason we had to upgrade in the first place was due to the 'white flash' problem when watching 1080p Blu-ray movies or Playstation 3 games. That was fixed in 4.24 if I can remember correctly.
Problem is that 4.24 then brought issues with the TV switching off for no reason. sw 5.00 fixed this, but then brought the other problem of a link room TV showing HDCP warnings without the 'master' being on at the same time. sw 5.08 apparently fixes that problem.
I heard from my dealer that they won't upgrade my TV and that they'll organise for a B&O engineer to visit!
If you do no have the initial white flash issues, I wouldn't bother upgrading! None of the software upgrades bring anything compelling, apart from new issues (and fixes).